Translating sleeve thrust reversers incorporate cascade assemblies which include pluralities of cascade segments, or baskets, spaced circumferentially around the engine nacelles. Each cascade segment includes a plurality of spaced airflow-turning vanes defining a series of cells or air passages. As seen in FIG. 1 (PRIOR ART), when the thrust reverser 40 is in a stowed configuration, the cascade segments 42 are covered and air flows through and rearwardly out of the engine to provide forward thrust. As seen in FIG. 2 (PRIOR ART), when the thrust reverser 40 is in a deployed configuration, the cascade segments 42 are uncovered and at least a portion of the air flowing through the engine is redirected through and forwardly by the vanes of the cascade segments 42 to provide reverse thrust.
Blocker doors 44 are used to redirect the airflow through the cascade segments 42. A drag link 46 actuates each blocker door 44 between closed and open positions which respectively correspond to the stowed and deployed configurations of the thrust reverser 40. In operation, an actuator mounted to a torque box translates a sleeve 48 rearward, and hinges mounted to the sleeve 48 pull the blocker door 44 rearward. The drag link 46 rotates around a pivot point and pulls the blocker door 44 upward, and the blocker door 44 rotates on the hinges to the open position. A control link allows limited relative motion and maintains tension in the stowed configuration.
However, the drag link 46 for actuating the blocker door 44 is exposed to the airflow through the engine during all phases of flight, regardless of the stowed or deployed configuration of the thrust reverser 40, which results in undesired drag. In one prior art solution, a track is provided for the drag link, but this does not allow for adequate control of the airflow during transition. One challenge is to open the blocker door sufficiently early in the deployment of the thrust reverser to avoid increasing the total airflow area too quickly and potentially causing damage to the engine. Prior art attempts have been made to use a telescoping drag link, but these have failed to provide adequate control of the airflow during the transition periods. In particular, the blocker door will not begin to deploy and redirect the air until the telescopic mechanism is fully extended. Other prior art solutions include complex actuation mechanisms and/or multiple linkages that interact to provide better potential transient control, but these suffer from increased complexity. One way to altogether avoid these problems is to replace the translating sleeve with pivot doors, but the latter typically provides less reverser efficiency than the former.
This background discussion is intended to provide information related to the present invention which is not necessarily prior art.